


OBEY ME - SIREN - MAMMON

by DizzyandKoko



Series: X READER [2]
Category: Shall We Date?: Obey Me!
Genre: Camping, F/M, No Smut, Sirens, Swearing, Vacation
Language: English
Status: Completed
Published: 2020-12-31
Updated: 2020-12-31
Packaged: 2021-03-11 00:01:51
Rating: General Audiences
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 2
Words: 3,231
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/28455765
Author URL: https://archiveofourown.org/users/DizzyandKoko/pseuds/DizzyandKoko
Summary: Mammon X ReaderGender: Female/She/HerY/N is a siren.Y/N and the brothers are taking a vacation at a cabin next to a lake and Y/N wants to go swimming in secret.Prompt by Dizzy(me).
Relationships: Mammon (Shall We Date?: Obey Me!)/Reader
Series: X READER [2]
Series URL: https://archiveofourown.org/series/1989976
Comments: 5
Kudos: 25





	1. Chapter 1

**Author's Note:**

  * Inspired by [HEADCANONS](https://archiveofourown.org/works/28480944) by [DizzyandKoko](https://archiveofourown.org/users/DizzyandKoko/pseuds/DizzyandKoko). 



~-~

I've wanted to get in the water since day one here. It was a white, cool looking lagoon with plenty of plants and smaller, less intelligent fish.

A few days ago, Diavolo invited us to take our summer break at one of his private vacation homes. We all agreed that the cabin would be a nice change of pace while still allowing us enough space so we don’t kill each other.

I always planned on trying to sneak out for a dip, but I was always too tired or busy to go out. But not tonight. 

I slowly opened my door and snuck out and down the hall. I could tell that some people were still up as quiet music and small lights still made the house alive. I was lucky that my genetics allowed me to easily slip down stairs.

I don't bother putting on my shoes as I'd just be taking them off right away, and with that, I exited the cute house.

I took the crispy air into my lungs. It was a refreshing cool night that contrasted the day's hot, sweaty atmosphere.

I ran off of the porch and striped off my socks and threw them to the wind. I moved towards the edge of the forest that surrounded the cabin and hid the lagoon from view. When I entered the forest’s pathway, I unbuttoned my jeans and hopped out of them, tossing them onto a tree with my underwear following suit. Sprinting through the small trail, I pulled off my white shirt and bra and threw them to who knows where.

Standing in the white, cold sand, I looked into the large yet modest lagoon. I could see the bottom of it with my special E/C eyes, no one else could see through water like I could. Every fish, plant, debris, trash and treasure that inhabited the water was visible to me.

I slowly walked along the transition from land to water. I could feel my fins jet out of my back and my fingers start to web. When I got waist deep in the water, my legs started to grow and morphed together into my extra long tail. 

As I could no longer stand up, I dived into the chilly water. I could hear just fine as my ears went fishy in the process. I went out farther into the water to get a better look at my tail. 

It was just perfect. The main color was bright F/C that faded into a mint blue with pastel purple stripes. It was just the smig bit taller than Beel and branched out into smaller fins to help me glide through the water.

I did a spin in delight before sinking deeper then shooting up into a dive out of the water and falling backwards. My friends back home copied this from some humpback whales we were messing with.

When I fell back into the water, I spotted a common carp. It clearly didn't know that I was from salt waters as it happy greeted me like they greet my freshwater friends. Well, I am anadromous so I could be considered freshwater native too.

The carp brought some of its friends over to meet me. Carp can't talk like I can, but I can understand their movements. I didn't like how attached they were to me already. The lagoon was closed off from any other rivers or lakes so they clearly don't understand much of the dangers of talking to new fish.

I decided to just get it over with and I scratched them, drawing blood. The venom from my claws took effect admediatly. I killed them and shoved the first into my mouth and held the others in my left hand. I tried getting the last one, but it swam away from my grasp.

The water was now uneasy, the other fish swam away to safety from my grasp. My gills puffed with bubbles and I floated back to the surface, tossing the first carp’s skeleton away in the process. 

I laid by my back on the water to finish the carp I caught. I hadn't had any good, fresh fish in a while. I don't hold it against Lucifer, Diavolo, Barbados, Mammon or any of the others. They just don't know how to take care of me right, they think I'm a human. They aren't damaging me or hurting me, just not caring for me right.

I'm glad that they think I'm human, I don't want to go through the trouble of what would happen if they found out.

Then, I tempered a game my friends and I played:

_Jumper._

It was simply stupid game, you’d just try and jump as high as you can and the highest jumper wins.

I smiled and I dived into the water and sat on the bottom. I recoiled my tail and steddied myself with my arms. _Jumper_ was harder than it looked, it requires a lot of strength, speed and coordination. It would be even harder this time as I didn't have experience with this lagoon. I didn't know where to land without hurting myself already in my memory like back home. So it would be a lot of guesswork, but I still wanted to try. I wanted to feel like I'm home.

With that, my tail extended in a flash and my arms further propelled me to the surface. I kept my limbs as close to me as possible to keep my drag down. 

I was now in the air. Yard by yard, I left the water. I could tell this was the highest I've ever been! I probably beat NAME’s record!

_$_

_Mammon: Hey, Y/N, I can’t sleep, can I come to your room?_

__

_Mammon: HELLO??? Ya there????_

__

_Mammon: Oi! Are ya ignoring me too?_

__

_Mammon: I know you can’t sleep through my notifications!_

_Mammon: Fine, I’ll just come to your room anyways._

Standing up, I threw my phone on my bed and put on only my pants. I peeked my head out of the door before sneaking out. It was past curfew and if Lucifer caught me, who knows how long he'd hang me.

I slowly went down the hall and opened her door. She wasn't here. Her bed was still made and her phone was plugged in, my messages still flashed on the screen before disappearing.

Where was she? She, besides Belphie, are probably the only ones who follow Lucifer’s stupid rule. Maybe she went to get some water down stairs.

I went down the stairs that lead into the kitchen. Nope. She wasn't here either. Did she leave the house? No, she wouldn't do that. Would she? Her shoes were still here.

Putting on my sandals, I opened the front door and walked out. The grass looked disterbed like someone walked through it. So Y/N did go outside. She must have gone to the lagoon, she loved hanging out there. 

I should go check on her, something must be wrong.

I walked over to the path in the forest that leads to the lake and saw… Socks? Did she take off her socks? Why? I looked further into the path and saw her jeans. Oh dear god, is she skinny dipping!?

Further down the path I found her shirt and bra hanging on branches. I rubbed my face, should I go check on her still, even though she's probably naked? Something might be wrong though, this isn't something she would do unprompted. I have to find what's wrong with her, even if she's wearing nothing.

She should be appreciative that _THE_ Great Mammon is coming to help. I exited the forest and walked onto the white, sandy, beach.

Where the fuck is she!?

Y/N just straight up disappeared, she's nowhere to be found! Did aliens take her? Are aliens even real? Never mind, I gotta find her!

Then, there was a loud splash as a mermaid jumped out of the water and several yards into the air. I stood there, gawking as I realized that the mermaid was Y/N. She's so graceful up in the air like that, her tail was so long and branched off into many different fins.

Y/N’s focus changed from the air to me, I could see her pleasant, calm demeanor change to horror. She lost her balance and fell face first back into the water with a big splash.

“Y/N!?” I yelled when she sunk back into the water. I started taking my pants off to jump in and save her. However, she resurfaced quickly and fanned her red face.

“Ow! Ow! Ow!” She repeated.

I sighed and fixed my pants. “Ya ok?” 

“Yeah, I will be!” Y/N looked to have sighed and calmed down, sinking back into the water up to her nose.

Y/N slowly made her way to the shour to meet me. I crouched down to her level to talk better with her only to remember that she had no closes on. I could feel my face heat up as I covered it, mummering apologies.

Y/N tisked. “Mammon, it's fine, I don't care if you see my boobs.”

“Yeah well I do, it's yer body, not mine and I wanna respect that.” I told her. “I'll go getta shirt.”

“No! Don't!” She jumped up to keep me from walking away, making me drag her tail in the sand. “I hate closes, I'm still not used to them, they're just so… Restricting and uncorterbul. They irritate my fins and stuff when I'm in this form.”

“Ok, I'll just keep my eyes covered.” I told her, flopping back into the sand.

There was an awquer silence between us for a moment. No one knew what to say. I was too stunned to make comprehensible sentences and I could tell that Y/N was selfconshoues about her body. 

“Mammon, I'll put on my bra at least. Can you get it?” Y/N asked.

I quickly stood up. “Gladly.”

I went into the forest’s trail and got Y/N’s bra from the tree it was hanging from. I ran back and handed her back her bra. I kept my eyes covered till she put it on.

With my eyes uncovered again, I could appreciate Y/N’s presence again. Her H/C hair stuck to her face from the lake’s water. Her skin was still slightly reddish from the belly flop from earlier. The beautiful E/C eyes sparkled from the moon’s light perfectly. And her tail was unforgettable too. It wasn't scaly like a salmon’s or Levi’s goldfish, it was still fleshy like a shark’s or manatee’s. Even without scales, it still had a glimer to it.

“You wanna touch it?” Y/N intrupeed.

“I what?” I looked into her E/C eyes in shock.

Y/N just giggled and raised the end of her tail out of the water, bringing it closer to us. “I asked if you wanna touch it. You were staring at it for a bit there.”

I dug my teeth into my lip as I brushed a few fingers across it. “Ew! It's slimy!” I recoiled my hand from Y/N’s tail and cleaned it off in the water.

Y/N just laughed at me, bringing a webby hand to cover her mouth. After I cleaned off my hand, I grabbed hers. Her once S/C hands were now colored like her tail and she didn't have any fingernails, only sharp claws instead. What was still the same, however, was her babysoft palms.

As I dragged my fingers along the webbing, Y/N’s other hand, inverted coloring this time, covered mine. “Be careful, they're sharp and venomous.”

“Can it kill me?” I asked, looking back into Y/N’s eyes.

She only smiled and shook her head. “No, it'll only parelise you for a few hours, probably. It's only meant to kill humans, pirates, fish, those sorts of creatures.”

“Lucky me.” I put her hands back on her ‘lap’ and sighed. “Is there a reason ya hid yer mermaid side from us?”

I saw her stiffen as I popped the question. She bit her lip with her razor sharp teeth lightly and looked away. “I…”

Behind us, from the forest, was the rustle of leaves and broken sticks and Levi came running out mad. “How are you two allowed out but not…!” Levi froze when he saw Y/N, who already scooted inwards into the water, ready to make her escape. “Me…?”

It went quite again as we stared at each other as if one of us had a gun. The tension quickly exploded as Levi screamed.


	2. Chapter 2

_$_

It went quite again as we stared at each other as if one of us had a gun. The tension quickly exploded as Levi screamed.

I jumped up and ran to cover his mouth, cutting him off. “What the fuck was that for, Levi?” I whisper yelled at him. I quickly checked to see that Y/N was almost fully back into the water, ready to run.

Levi then licked my hand, making me let go of him. “What the fuck was that for? Of course I'd yell seeing Y/N with a tail!”

“SHHH! Don't yell, I don't want Lucifer-”

Lucifer came running out. “Mammon! Levi! What happened!? Where’s Y/N? Why’s her clothes littered on the trail?”

Y/N made a loud gasp and dived back into further waters. The lake water was only a little disterbed.

“What the hell!?” Lucifer ran closer to the water. “Was that…?

I nodded. “Yeah, that’s Y/N. But thanks to you, she ran away.”

“More like swam away.” I heard Asmo snicker.

Levi put his hands into his pockets. “It reminds me of this plot twist in ‘ _Help! My Love is Trying to Murder Me and as A Last Ditch Atempt to Get Away I Joined A Salon and Became A Male Protatot That Allowed Me to See The Eyes of_ -’ ”

“No one cares!” I yelled into Levi’s face.

“Shut up, you two!” Lucifer hit Levi and I over the backs of our heads. “The point is that Y/N was secretly a mermaid and is now probably at the bottom of the lagoon and we have to try and get her back.”

Satan then joined up on the beach. “Acully, Y/N appears to be a Siren. They're cousins of the mermaid but have evolved into two different speeches.”

I raised an eyebrow. “What's that gotta do with this?”

“Everything. Sirens have blood that, when treated, can be used for healing. However, it takes a lot of blood before any healing can be done. Specifically, to heal one, lets say, human, you'd need three liters of treated Siren blood per liter of human blood, effectively killing the siren.” Satan told us.

Lucifer put a hand to his chin. “So, going off of what you said, Y/N must think we are after her blood.

“Damn.” Beel said before looking out into the lake. We could see Y/N’s head popped out of the water, watching us. “So she must be scared of us.”

“No, she's scared of y'all!” I pointed at them. “She was fine with me here all by our lone selfies. But when you showed up and started screamin’, she went swimmin’ with the fishes!”

Asmo soffended his eyebrows. “As dumb as it sounds, he does have a point, you all where yelling an awuffel lot.”

Lucifer pinched the bridge of his nose. “I get that, but how are we going to get her back? We can't leave her out in the open like this. Someone could randomly come along and kidnap her for her blood.” He paused for a minute to think. “Levi. Can you try and catch her?”

“Waoh! Waoh! WAOH! We can't do that, it'll just scare her even more. Also, she told me that she can paralyze us for a few hours with her poison.”

“It would be venom.” Satan corrected me.

Asmo sighed. “As much as I love Y/N, I love my beauty sleep more, I don't want to wake up with dry skin! I'm going back to cuddle with Belphie! Good night, have fun!” 

“Yeah, good night.” I hissed under my breath.

Lucifer loudly sighed. “So, what are we going to do? Just wait here for her to get back!?”

Beel shrugged his shoulders. “I mean, it could work, but I don't think anyone wants to say out here, it's almost one in the morning.”

“And I have a game event in an hour, I should be getting ready!” Levi started running back to the house.

Beel looked at us with a look of guilt before slowly stepping closer to the path and disappearing.

“I'm assuming you're staying out?” Lucifer asked.

“Yeah, I don't see any reason why not.” I answered.

“Ok,” Lucifer ruffled my already messy hair, “try not to stay out too late, it's already two hours past curfew.”

He patted my back before disappearing like the rest of them.

~-~

I saw Lucifer ruffle Mammon’s head before walking back to the cabin. Mammon sat down and crossed his legs, resting his head on his palms. Even from here, I could tell he was tired. I caused this, if I just stayed put, I could have prevented this and he could be in his bed sleeping.

My gills sighed and I dived into the water to swim to sour. I reached the drop off quickly and popped my head back out of the water, my tail could now brush the bottom of the lagoon like a bhrum. Mammon sat up seeing me.

“Your back, that was quick.” He walked closer to the water and crouched down to my level.

“I… Didn't want to wait on me… You're tired and shouldn't be out here and… And… I just don't want to force you to wait for me… And I'm kinda done here anyways…” I rambled.

“Ok, but wouldn’t ya want to be in the water yer species is meant to live in?” Mammon asked.

I shook my head. “I belong in the Devildom with you and everyone else. The Devildom is my home now.”

Mammon smiled with a small blush.

I stuck my tongue out at him. “Now, can you get me my chloes now? I know how you get when I don't have any.”

His small blush turned into a much bigger one. “I… Um… It's somethin’ that's not, not normal in th, the Devildom.”

Mammon got up and ran to get my cloeas and I started morphing my body back into my human form. My tail shrunk and split into two different limbs; my fins, webbing and claws disappeared besides for my gills on my neck. They just went flat and camouflaged into the rest of my S/C skin. Without my tails or fins, it was much harder to swim to sour.

When I sat in the sand, legs still submerged in the water, I rung out my hair to get rid of the excess water. I even pulled a fish skeleton from it.

Mammon walked back over to me with what's left of my chloes and his eyes covered. I thanked him and dressed myself.

After, I wrapped my arm around Mammon’s for support and we walked back to the cabin.

**Author's Note:**

> Ok, so I got really into making a siren mythology while world building for this. Would you like me to post what I have about my take on fairytale things? It is not going to be like when I say I'm going to do something then I don't as I already have two chapters written for it, haha.
> 
> (I made the story, I have a bit more info on my take of Sirens and Marmaids)
> 
> I got inspired by SuperRandomWriter from Wattpad, go check them out, they have really sick-o-mode stories.
> 
> Anyways, I hope your New Year will be fucking better then 2020, stay safe!  
> -Dizzy


End file.
